What is the definition of "Ir Chomah"?
Rashi: It is a town that had a surrounding wall from the days of Yehoshua bin Nun. 1
What is the smallest size house that the owner may redeem only up to a year?
Sukah, 2b: A room 1 of four by four by four Amos. Less than that, has the Din of a house in an open town.
Regarding most issues, 'Bayis' means a room.
What distinction does the Pasuk draw between the sale of a field and the sale of a house in a walled town?
Rashi: Whereas the former may redeem his field after two years, the latter may only redeem his house during the first year, but not afterwards.
What are the implications of "Vehaysah Ge'ulaso ad Tom Sh'nas Mimkaro"?
Erchin, 31b: It implies that, if the owner dies, his son is permitted to redeem the field in place of his father, 1 and that, if the purchaser dies, the owner is permitted to redeem it from his son. 2
Why does the Torah permit redeeming a house in an open town until the Yovel
Ramban and Moshav Zekeinim: Because on the one hand, selling a house is initially difficult and embarrasing for the owner; therefore the Torah allows him to redeem it within a year. However, having sold it and not redeemed it within the year, he has evidently despaired of redeeming it and the sale becomes permanent. 1 A house in an open town on the other hand, 2 which also serves to guard one's fields, has the same Din as the fields. 3
Torah Temimah, note 149: Or because he has settled down in his new house and no longer pines for the olr one. Perhaps the Torah is also concerned lest people will be loathe to buo a houses if the seller can redeem it at any time (PF).
Which, as opposed to one in a walled town, is located near his field.
Why does the Torah add the 'Vav' at the end of "Sh'nas Mimkaro"?
Targum Onkelos and Targum Yonasan: It implies a full year from day to day, and not until the end of the year (Erev Rosh ha'Shanah). 1
Da'as Zekenim: This Parshah alludes to Hashem, who 'sold Eretz Yisrael to Bavel' for seventy years (due to the seventy Sh'mitah years that Yisrael did not observed). At the end of this time, He will redeem the sale (return the land to Yisrael). 2
What is the meaning of "Yamim" (on its own)?